GAP SEAL

Abstract: Seal for a gap between structural elements such as between panels in building structures, the seal being in tubular form which is flexible and resiliently radially compressible and which provides a fire-resistant barrier in fire conditions, and being based on a composition comprising elastomeric material and intumescent material in major proportions.

Description: GAP SEAL This invention relates to gap seals, especially to seals for gaps between structural elements such as panels in building structures. Gaps at the junction of structural panels, such as walls, ceilings and floors of buildings, frequently are provided to allow for small movements between the panels. The present invention provides a seal or joint for installation in such gaps, and which accommodates variation in the size of the gap and changes in the gap size resulting from movement of the panels, for instance by expansion or contraction or lateral movement of one or more adjoining panels. Such seals are sometimes referred to as expansion joints. The seal or joint of this invention also provides a fire-resistant barrier seal which additionally may confer thermal and/or acoustic and/or moisture insulation. The seal of the invention has a tubular form. It is flexible and is resiliently radially compressible. The tube may be produced in long lengths, for example by extrusion, for cutting to lengths required for the gap to be sealed. The seal is based on a composition comprising elastomeric material and intumescent material. Preferred additional ingredients include a fire-retardant agent and/or a fusible inorganic binder. Other suitable ingredients include a reinforcing filler and/or a light¬ weight filler. One or more additional ingredients, such as those known for use in elastomeric compositions, may also be present. If desired, the seal may comprise a laminate of the composition with one or more layers of other material. The elastomeric material provides a binder for the other composition ingredients. Suitably, it may be a synthetic rubber. Preferably it is curable at a temperature lower than that at which the intumescent material commences to intumesce. A preferred elastomeric material is epdm. A suitable intumescent material is expandable graphite material. Such material usually comprises chemically-treated graphite which commences to expand by several times its original volume, e g 100-200 times, when heated above a critical temperature, e g about 190 ° C. Examples of expandable graphite materials are those available under the trade name 'CALLOTEK', for instance 'CALLOTEK 100' or 'CALLOTE 500'. Preferably, the composition contains a high proportion of intumescent material. For instance, the ratio of intumescent material to elastomeric material may be at least 1 :1 by weight. The fire-retardant agent suitably is an ablative material. A preferred fire-retardant agent is alumina trihydrate. It is found that alumina trihydrate also enables an increase in the temperature employed for curing the elastomeric material in the composition without premature activation of the intumescent material. The fusible inorganic binder is a material which is capable of melting and resolidifying at elevated temperatures such as fire temperatures. A preferred fusible material comprises glass particles. Preferably the fusible material comprises a mixture of particles having different melting points, suitably commencing at about 200 ° C. Such a particle mixture may melt progressively over a temperature range of about 200 ° C to 900 ° C, for instance about 350 ° C to 700 ° C. The material then resolidifies above the melting temperature. For instance, resolidification may commence at a temperature above about 700 ° C or above about 900" C to form a crystalline solid. In doing so, it acts as a binder for maintenance of stability of the seal in fire conditions. Examples of suitable fusible glass particles are those available under the trade name "Ceepree" ex ICI/Brunner Mond & Company. A suitable reinforcing filler for the composition is carbon black. A suitable light-weight filler may be, for instance, hollow microspheres such as polymeric microbalioons. The polymeric microbalioons preferably are of a resilient material, for example epdm. Suitable resilient microbalioons are those obtainable under the trade name 'EXPANCEL'. Other ingredients may be selected from, for example, curatives, accelerators, processing aids, anti-ageing agents, fungicides, pigments, fibre reinforcements, etc. By way of example only, a composition suitable for a seal or joint according to the invention may have the following formulation:- Inαredienτs Parts by weight Elastomer (epdm) 100 Intumescent agent (expandable graphite) 100-200 Fire-retardant agent (alumina trihydrate) 20 Fusible inorganic particles ('Ceepree') 10 Filler (carbon black) 30 Light-weight filler ('EXPANCEL') 10 Other ingredient(s) 5 The composition ingredients may be blended by conventional techniques. The tubular form of the seal may be produced by, for instance, extrusion of the composition. The composition may be subjected to elastomer-curing conditions in its tubular form. The cure temperature preferably should be below that at which the intumescent material would start to intumesce. An example of a suitable cure temperature is about 150 ° C. The seal is suitable for indoor and outdoor applications. Suitably the external diameter of the seal in its uncompressed state is greater than the width of the gap to be sealed, so that the seal is held in compressed state in the gap. A preferred level of compression of the seal in the gap is at least about 20% of the uncompressed seal diameter. The tubular wall thickness of the seal preferably should be such that, when the seal is subjected to fire conditions which degrade the elastomeric material, the composition expands intumescently into the hollow of the tube and across the gap to maintain or increase the barrier effect of the seal, and thereby prevents traverse of flame, smoke and other hazardous fire products. The ratio of the tubular wall thickness to the uncompressed seal external diameter may be in the range of, for instance, 0.08:1 to 0.5:1. Preferably the ratio is at least about 0.1 :1. By way of example only, dimensions and corresponding compressions of the seal are given below, in which:- W = gap width; CD = compressed external diameter of the seal along the depth of the gap; UD = external diameter of the seal in its normal uncompressed state; C = compression of the seal widthwise of the gap. CD : W W : UD C (%) 1 :1 0.785: 1 21.5 2:1 0.523:1 47.7 3:1 0.393: 1 60.7 4:1 0.314:1 68.6 5:1 0.262:1 73.8 15:1 0.098:1 90.2 The cross-sectional outer shape of the tubular wall of the seal (i e in a plane perpendicular to the longitudinal axis of the tube) may be of any shape suitable for fitting the seal into the gap to be sealed. Typically, the tubular wall of the seal, in its normal uncompressed state, has a substantially circular cross-sectional surface shape, but alternatively it may have, for instance, an elliptical or a polygonal outer surface shape. Optionally, the seal may be provided with one or more longitudinal slits in the wall, extending from the external surface thereof, to facilitate compression for insertion into a gap. One such slit may penetrate completely through the wall if desired, and in that case the seal preferably should be located in the gap such that the slit is not exposed.

Claims: CLAIMS: 1 . Seal for a gap between structural elements such as between panels in building structures, characterised in that the seal is in tubular form which is flexible and resiliently radially compressible and which provides a fire- resistant barrier in fire conditions, and said tubular seal is based on a composition comprising elastomeric material and intumescent material in major proportions. 2. Seal according to Claim 1 wherein the intumescent material comprises expandable graphite. 3. Seal according to Claim 1 or 2 wherein the ratio of intumescent material to elastomeric material is at least 1 : 1 by weight. 4. Seal according to any of the preceding Claims wherein the elastomeric material comprises epdm. 5. Seal according to any of the preceding Claims wherein the composition comprises also a fire-retardant agent. 6. Seal according to Claim 5 wherein the fire-retardant agent comprises alumina trihydrate. 7. Seal according to any of the preceding Claims wherein the composition comprises also a fusible inorganic binder being a material which is capable of melting and re-solidifying at normal fire temperatures. 8. Seal according to Claim 7 wherein the fusible inorganic binder comprises a mixture of glass particles having various melting points. 9. Seal according to any of the preceding Claims wherein the composition comprises also one or more fillers. 10. Seal according to Claim 9 wherein the composition contains light¬ weight filler being resilient microbalioons of polymeric material. 1 1. Seal according to any of the preceding Claims having a tubular form produced by extrusion. 12. Seal according to any of the preceding Claims wherein the ratio of the tubular wall thickness to the external diameter of the seal in its uncompressed state is in the range 0.08:1 to 0.5:1. 13. Seal according to Claim 12 wherein said ratio is at least 0.1 :1 . 1 . Seal according to any of the preceding Claims which, when present in a gap as a gap seal between structural elements, is under radial compression by at least about 20% of the uncompressed seal diameter. 15. Seal according to any of the preceding Claims having one or more longitudinal slits in the tubular wall, extending from the outer surface of the wall.

Inventors: GANENDRAN ARASAPILLAI NADARAJA, GANENDRAN, ARASAPILLAI, NADARAJAH
Applicants: BTR PLC, GANENDRAN ARASAPILLAI NADARAJA, GANENDRAN, ARASAPILLAI, NADARAJAH
Application year: 1994
Main classification: E04B1
IPC codes: E04B1